Ubuntu 20.04 and kernel issues | need cp210x kernel module

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Viss
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Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

I've followed several guides to install ubuntu onto an odroid-u2.
It boots, it runs, but the purpose of this unit is to act as basically an emergency terminal-server to serial into some equipment.

The problem I'm running into is somewhat of a cascade - the equipment I'm trying to serial console into registers as a 'Silicon Labs CP210x UART Bridge", which on any other linux installation would appear as /dev/ttyUSB0 and the command "screen /dev/ttyUSB0 115200" would connect me to the serial terminal.

However on this odroid, it appears the cp210x kernel driver is missing, so I tried to upgrade the kernel. I got to 4.16.0-v7, which doesnt have that driver, and I can't seem to apt-get my way to success here. I attempted to download the driver source directly from silicon labs, but when attempting to compile it, make complains that the kernel sources are missing - the sources for that kernel aren't in apt, and understanding the odroid kernels are customized I wasn't sure if just fetching the raw sources and plopping them in the right places would do it.

It's also apparently impossible to just apt-get any 5.x kernels from apt, because despite them "getting installed", ubuntu doesnt understand that stuff lives in /media/boot and while the OS thinks there's a new kernel there, upon reboot the system still loads 4.16.0-v7.

tl;dr I need to get that cp210x kernel module loaded so I can use this odroid for a serial console. I would prefer a more recent kernel, but honestly at this point however it needs to happen to get that functionality out of this odroid, I'm all ears.

thanks in advance!

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by odroid »

If you don't mind, try old Ubuntu 16.04 LTS image with an ancient Kernel 3.8.
That image has cp210x module by default.
https://github.com/hardkernel/linux/blo ... nfig#L3105

The OS image file name is ubuntu-16.04-mate-odroid-u2u3-20160920.img.xz
https://odroid.in/ubuntu_16.04lts/


BTW, where did you download the Ubuntu 20.04 image?

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

I didnt get an image - i installed the 16.04 image that you linked above (that exact one, actually)
then did apt-get dist-upgrade to bring it to current, then do-release-upgrade -d a couple times, and it was able to get upgraded all the way to 20.04.
Problem is the only thing (literally, the ONLY THING) that didn't make it across was the kernel. Everything else works like a champ.

To do what you're suggesting, I'd have to simply format the entire thing and start from scratch. Considering this device is going into the office a computer security company, I would prefer not to run ancient, exploitable kernels, as there is liability here.

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by odroid »

Since we've never released Kernel 4.6 officially, we don't know how you can upgrade the kernel.
Can you show me uname -a output on your current image?

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

Linux odroid 4.16.0-v7 #1 SMP PREEMPT Mon Apr 2 11:02:49 UTC 2018 armv7l armv7l armv7l GNU/Linux

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by odroid »

Very weird. :o

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

hey, it totally works, and for this super low complexity, super low impact thing I need this odroid for, the last hurdle is just getting that one kernel module, either into this kernel, or into, preferably, a 5.x one.
doing a dist-upgrade on this thing takes literally half a day because its ancient, so ideally i'd prefer not to have to compile my own kernel from scratch on here, especially since it seems difficult to get kernel source out of apt anyhow. Do you have any suggestions I could try, besides going to a kernel that would be trivially exploited by anyone who knows about the linux exploit suggester bash scripts?

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by odroid »

I really don't have any idea where the kernel source comes from.
So it is hard to help you.

I hope other users can't give you some ideas.

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

here's something that would really help - these are the current sources in /etc/apt/sources.list

deb http://ports.ubuntu.com/ubuntu-ports/ focal main universe restricted multiverse
deb http://ports.ubuntu.com/ubuntu-ports/ focal-backports main restricted multiverse
deb http://ports.ubuntu.com/ubuntu-ports/ focal-security main restricted multiverse universe
deb http://ports.ubuntu.com/ubuntu-ports/ focal-updates main universe restricted multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports/ focal main universe restricted multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports/ focal-backports main restricted multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports/ focal-security main restricted multiverse universe
deb-src http://ports.ubuntu.com/ubuntu-ports/ focal-updates main universe restricted multiverse


Could you post the official odroid ones?
Perhaps I could apt-get a functional kernel from those.

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

odroid wrote:
Fri Mar 27, 2020 9:45 am
If you don't mind, try old Ubuntu 16.04 LTS image with an ancient Kernel 3.8.
That image has cp210x module by default.
https://github.com/hardkernel/linux/blo ... nfig#L3105
Per your instructions, I have gone back to the 16.04 official image.
I have attempted exactly the same thing, and I have exactly the same problem.

This shows up in dmesg:
[ 70.449490] usb 1-3.1: USB disconnect, device number 4
[ 72.283398] usb 1-3.1: new full-speed USB device number 6 using exynos-ehci
[ 72.436236] usb 1-3.1: New USB device found, idVendor=10c4, idProduct=ea60
[ 72.436242] usb 1-3.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 72.436247] usb 1-3.1: Product: CP2104 USB to UART Bridge Controller
[ 72.436251] usb 1-3.1: Manufacturer: Silicon Labs
[ 72.436255] usb 1-3.1: SerialNumber: 015EFC00
but /dev/ttyUSB0 doesn't get created, and the odroid won't communicate with the serial-over-usb connection.

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by odroid »

Our Kernel 3.8 config file says the CP210x driver should be enabled as a module.
https://github.com/hardkernel/linux/blo ... nfig#L3105

Check "lsmod" output.

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by Viss »

root@odroid:~# lsmod
Module Size Used by
joydev 20480 0
evdev 24576 1
ipv6 393216 26
root@odroid:~# modprobe cp210x
modprobe: FATAL: Module cp210x not found in directory /lib/modules/4.16.0-v7
root@odroid:~# modprobe cp210
modprobe: FATAL: Module cp210 not found in directory /lib/modules/4.16.0-v7
root@odroid:~# find /lib/modules -iname \*cp210\*
root@odroid:~# uname -a
Linux odroid 4.16.0-v7 #1 SMP PREEMPT Mon Apr 2 11:02:49 UTC 2018 armv7l armv7l armv7l GNU/Linux

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Re: Ubuntu 20.04 and kernel issues | need cp210x kernel module

Post by odroid »

You didn't flash our 16.04 OS image.
Double check the file name. If you install that image, the kernel version must be 3.8.y.
ubuntu-16.04-mate-odroid-u2u3-20160920.img.xz

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